Here are some sample menus...I have to say, having been on many =X= cruises, the food is wonderful. There was a "rough patch" about a year ago, but I think it has improved.

If you will be on a Millennium class ship, the Aqua Spa Cafe has great menu options that are usually low fat or low carb / low sodium. The main dining rooms have their own menu, as does the specialty restaurants. Here's a sample: